The heavy lifting is pretty much over for the Miami Dolphins’ starters as they head toward the Sept. 9 opener against Tennessee, so it’s time for a unit-by-unit glimpse at what we’ve learned about this team through three preseason games and training camp.

The grades are weighted about 80 percent toward the starters, but reserves are considered because, let’s face it, injuries happen.

For these purposes, we’ll use the following guide for the grades…

A: Super Bowl or conference championship level

B: Playoff level

C: Average, symbolic of a 7- to 9-win team

D: Below average, symbolic of a 4- to 6-win team

F: Not NFL-caliber

OK, on to the report card.

QUARTERBACK: B-

Ryan Tannehill can do the job, but he needs help in the form of a running game and defense. Overall, he appears at the peak of his game, which might or might not be good enough to carry this team to the playoffs (we’ll give...